Pulse generating apparatus

ABSTRACT

A condenser discharge type electrical pulse generating circuit, such as for a combustion engine ignition system, wherein two storage capacitors are charged in parallel to discharge across a relatively low-voltage trigger gap which connects the condensers in series to discharge across a higher voltage control gap and through a relatively low-voltage ignition gap which is connected in series with the control gap. The above circuit is disclosed herein as being used in combination with a second, alternatively employed ignition circuit which supplies higher energy pulses for short periods, as during the starting of the engine.

United States Patent 1,997,064 4/1935 Lusignan Inventor Earl M. PhinneyOneonta, N.Y. Appl. No. 860,890 Filed Sept. 25, 1969 Patented Nov. 9,1971 Assignee The Bendix Corporation PULSE GENERATING APPARATUS 13Claims, 1 Drawing Fig.

US. Cl 307/106, 307/1 10 Int. Cl H02m 3/18 Field of Search 307/110, 106;315/209; 320/1 References Cited UNITED STATES PATENTS 2,524,240 10/ l950 Titterton et al 307/] 10 X 3,223,887 l2/l965 Brown .4 320/] X3,505,533 4/1970 Bernstein et al. 307/110 Primary Examiner-Robert K.Schaefer Assistant Examiner-William J. Smith Attorneys-Flame, Arens,Hartz, Hix & Smith and Raymond J. Eifler ABSTRACT: A condenser dischargetype electrical pulse generating circuit, such as for a combustionengine ignition system, wherein two storage capacitors are charged inparallel to discharge across a relatively low-voltage trigger gap whichconnects the condensers in series to discharge across a higher voltagecontrol gap and through a relatively low-voltage igni- -tion gap whichis connected in series with the control gap. The

above circuit is disclosed herein as being used in combination with asecond, alternatively employed ignition circuit which supplies higherenergy pulses for short periods, as during the starting of the engine.

PAIENTEDnnv 9 Ian INVENTOR.

EARL M. PH INNEY ATTO NEYS i PULSE GENERATING APPARATUS This inventionrelates to electrical apparatus and more particularly to means forcontrolling the operation of electrical pulse or spark generatingapparatus having an intermittently discharged storagecondcnser. 7

An object of the present invention is to provide novel conand a mainrelatively large tank condenser 20 connected across condensers l5 and 17in series. I

The high-tension side 'of the charging circuit is connected through adiode 18 to one terminal of a main storage condenser 20, the otherterminal of which is connected to ground. The condenser 20 is shunted bya resistance 28. it will be apparent that with thediodes l6 and 19connected as shown,

trol means for an electrical pulse or spark generating apparatus of thetype indicated.

Another object is to provide novel control means for an electrical pulseor spark generating apparatus incorporating a storagecondenser which isintermittently discharged through a control gap.

A further object is to provide means for controlling breakdown of thecontrol gap, such means being subjected to only a small part of theenergy which is discharged through the control "gap.

A still further object of the invention is to provide a control meansfor electrical pulse generating apparatus which is simple, rugged, andlong lived, and which provides maximum power output for a given inputvoltage.

Yet another object of the invention is the provision of a dual-energycircuit which employs a substantial number of components in common, one.part of the dual-energy circuit being of the above-indicated type.

The above and further objects and novel features of the invention willmore fully appear from the following description when the same is readin connection with the accompanying drawing. lt is to be expresslyunderstood, however, that the drawing is for the purpose of illustrationonly, and is not intended as a definition of the limits of theinvention.

The single FIGURE of the drawing is a wiring diagram of one embodimentof an electrical pulse or spark generating circuit in accordance withthe invention.

The circuit shown in the drawing is adapted for use as an untimedignition circuit for jet and gas turbine-type engines. The invention isnot, however, limited to such uses or systems.

The ignition circuit shown is a dual-energy system wherein one part, theupper part in the drawing, is adapted for intermittent operation at ahigh level of energy delivery, and the other part of the circuit, whichincludes some of the components of the one part, is adapted forcontinuous or substantially continuous operation at a lower level 'ofenergy delivery. Both parts of the circuit are of the condenserdischarge type. The lower energy, continuous service circuit will bedescribed first. Parts in the portion of the higher energy, intermittentservice circuit, which will be described later, which are the same orsubstantially the same as-those of the first-described circuit will bedesignated by the same reference characters with an added prime.

The lower energy part of the circuit shown i'senergized by a suitablesource 13 of alternating electrical current or a source of interrupteddirect current which is connected to input terminals B and C of suchpart of the ignition circuit upon the placing of switch S in its lowerclosed position. The current source is connected to the primary winding10 of a power input transformer 11 having asecondary winding 12. Thecircuit includes a radio frequency filtering means 14 which ispreferably, although not necessarily, employed, the means 14 beinginterposed between the power source and the transformer 11 to attenuatehigh frequency noise generated within the ignition circuit and thuspreventing interference from being transmitted to other circuitsconnected to the current source.

A voltage doubling type of energy storage means is connected across thesecondary winding 12 of transformer ll. Such storage means isincrementally charged by the energy source through transformer 11; theenemy storage means is periodically discharged to a pulse absorbingload, which in this instance is an ignition spark gap 29. The storagemeans comprises a small condenser 15 which is connected across thesecondary winding 12 through a diode or half-wave rectifier 16, a secondsmall condenser 17 connected across winding 12 through a reverselypolarized diode or half-wave rectifier l9,

when the condensers are being charged the lower terminals of condensersl5, l7, and 20 are negative whereas the lower terminal of a condenser31, tobe described, is positive. The diodes l6 and 19 may be protectedagainst damage, the operating life thereof may be enhanced, and therequired rating thereof may be minimized by providing current limitingresistors 21 and 22 in the circuit, as shown. One side of theabove-described energy storage means is shown as being connected to acommon ground 23, and the high-potential side thereof is connectedthrough a control gap 25 to the ungrounded electrode of an ignitionspark gap 29. It will be understood that, if desired, all of the pointsin the circuit designated 23 may be connected by a common ungroundedconductor.

The input electrode 24 of control gap 25 is connected to the highpotential side of the ignition circuit beyond the main tank condenser20. The output electrode 26 of the control gap 25 is connected to theinput terminal of two parallel connected choke coils 27, the outputterminals of the coils 27 being connected to the ungrounded electrode ofthe ignition spark gap 29, the other electrode of which is connected toground. The gap 29 is of the low-tension, shunted gap type, theelectrodes of the gap being bridged by a surface resistanceschematically shown at 35.

Connected across the series connected diode l8 and control gap 25 is acircuit having a resistance30 and a small condenser 31 in series.Connected to the high-potential side of the ignition circuit between oneterminal of the condenser 31 and the choke coils 27 is one terminal of aresistance 33, the other terminal of which is connected to ground. Theother terminal of condenser 31 is connected beyond resistance 30 to theinput electrode 34 of a trigger gap 36,.the other electrode 37 of whichis connected to ground. The ionizing or breakdown voltage of the triggergap 36 is substantially less than that of the control gap 25; thebreakdown voltage of the ignition gap 29 is less than the breakdownvoltage of the trigger gap 36.

[none successful embodiment the power transformer 11 steps up the supplyvoltage, which in this instance may be assumed to be 400 cycle, volt, toa level in excess of 1,400 volts peak. Each half cycle of this voltageis rectified by one of the diodes 16 19 to charge one of thedoublercondensers l5, 17. The voltage across condensers l5, 17 isadditive and therefore the voltage charging the main storage condenser20 and trigger condenser 31 is in excess of 2,500 volts peak.

While the storage condenser 20 is being charged, condenser 31, which isthen connected in parallel therewith, is charged through resistance 30,the charging circuit for condenser 3] being completed to ground throughresistance 33. As above explained, with the diodes l6, 19 disposed asshown, the input electrode 24 of. the control gap 25 is positive withrespect to the output electrode 26 thereof. When the trigger gap 36breaks down, the positive end of condenser 31, that is, that connectedto electrode 34 of the trigger gap 36 is momentarily to be connected inseries through the trigger gap and the voltages of condensers 20 and 31to be additive. Such added voltages exceed the 3,000-volt ionizingpotential of the main con trol gap 25. Gap 25 now begins to conduct thecharge of the main storage condenser 20 through the choke coils 27 andthe ignition gap 29 to ground, gap 29 having now been renderedconductive by subjecting it to a voltage in excess of its ionizingvoltage.

It should benoted that with this type of circuit the trigger gap 36controls the ionization of the main control gap 25. The normalionization voltage of the control gap 25 is much higher than the levelat which is is triggered. The trigger gap 36 in the disclosed circuit issubjected to only 5 percent of the energy being discharged through thecontrol gap 25. As a result, the life of the trigger gap 36 is greatlyincreased.

The portion of the circuit thus far described is adapted for continuousoperation, as for constantly supplying low energy level ignition sparksto an operating engine. in the circuit shown, there is provided afurther circuit portion which supplies high-energy level ignition sparksto an engine during this starting. Such further circuit portion isenergized from current source 13 when switch S is in its raised closedposition, thus also deenergizing the transformer 11 of the firstdescribed circuit part. A voltage doubler is supplied by the secondary12' of transformer 11'; the output of the voltage doubler 16', l9, l,and 17', is applied through a resistor 21' to the junction between thecondenser and electrode 24 of control gap 25. lt will be apparent thatin this mode of operation, condenser 31 is not charged during thecharging of condenser 20.

The voltage supplied by secondary 12 of transformer 11, when doubled bythe voltage doubler, exceeds the breakdown voltage of the control gap25. When condenser 20 is charged to a potential exceeding the breakdownvoltage of gap 25 and hence of igniter gap 29, the condenser 20discharges its energy through control gap 25, choke coils 27, andignition gap 29.

Typical values of component parts which make up the above describedsystem are as follows:

High-energy circuit 10.0-1 3.7 Joules Low-energy circuit 5.4-7.5 JoulesAlthough only a single embodiment of the invention has been illustratedand described in the foregoing specification, it is to be expresslyunderstood that the invention is not limited thereto but may be embodiedin specifically different circuits. For example, the main tank orstorage condenser 20 may be incrementally charged by means other thanthe voltage doubling system shown. For example, such condenser may becharged directly from the secondary winding of a step-up transformerpowered by an alternating current source. Such transformer may also bepowered by an interrupted direct current source. Various other changesmay also be made, such as in the electrical values suggested herein byway of example, and in the types of rectifiers illustrated withoutdeparting from the scope of the invention as will now be apparent tothose skilled in the art.

What is claimed is:

1. Electrical apparatus having a source of electrical energy, amultisection storage condenser connected to said source so as to beincrementally charged thereby with sections of the condenser connectedin parallel, a load circuit including a discharge gap connected to beenergized by the discharge of one section of the storage condenser, afirst control gap interposed between said one section of the storagecondenser and the discharge gap, a second control gap having a breakdownpotential less than that of the first control gap and less than thevoltage of the charge attainable by the parallel connected sections ofthe storage condenser, first circuit means connecting the second gap toanother section of the storage condenser to that the second gap isionized and rendered conductive when the charge on the parallelconnected sections of the storage condenser reaches the breakdownpotential of said second gap, and second circuit means for thereuponconnecting said sections of the storage condenser in series andsubjecting the first gap to the full voltage of the series connectedsections of the storage condenser to as to ionize the first gap andrender the same conductive to discharge said one section of the storagecondenser to the discharge gap independently of the second gap.

2. Electrical apparatus according to claim I wherein the storagecondenser has two sections, and the second circuit means includes thesecond gap interposed between the junction between the condensersections and a common conductor to which the load circuit is connected.

3. Electrical apparatus according to claim 1 wherein said one section ofthe storage condenser has a capacity which is substantially greater thanthat of the other condenser section.

4. Electrical apparatus according to claim 1 wherein the discharge gapis a shunted surface gap.

5. Electrical apparatus according to claim 1 comprising a choke coilinterposed between the first control gap and the discharge gap.

6. Electrical apparatus according to claim 4 wherein the spark-overvoltage of the discharge gap is less than the breakdown potential of thefirst gap.

7. Electrical apparatus according to claim I wherein the breakdownpotential of the first gap is less than the sum of the voltages of thecharges attained by said sections of the storage condenser when thesecond gap is ionized.

8. A dual-energy electrical pulse generating apparatus having twosources of electrical energy, a multisection storage condenser, meansselectively connecting the condenser to a first of said sources so as tobe incrementally charged thereby with the sections of the condenserconnected in parallel, a load circuit connected to be energized by thedischarge of the storage condenser, a first control gap interposedbetween at least one section of the storage condenser and the loadcircuit, a second control gap having a breakdown potential substantiallyless than that of the first control gap and less than the voltage of theparallel connected sections of the storage condenser as charged by saidfirst source, first circuit means connecting the second gap to thestorage condenser so that the second gap is ionized and discharged whenthe parallel connected sections of the storage condenser reach theircharged condition, and second circuit means for thereupon connectingsaid sections of the storage condenser in series and subjecting thefirst gap to the full voltage of the series connected sections of thestorage condenser so as to ionize the first gap and discharge said onesection of the storage condenser to the load circuit, and alternativelyoperated means selectively connecting said one section only of thestorage condenser across the second of said sources to be chargedthereby, whereby the first control gap is then discharged when thecharge on the said one section of the storage condenser attains thebreakdown potential of the first gap.

9. A dual-energy electrical pulse generating apparatus according toclaim 16, wherein said one section of the storage condensersubstantially exceeds the other section thereof in capacity, and thesecond source of electrical energy has a potential greater than that ofthe first source.

ll). Electrical pulse generating apparatus comprising a source ofelectrical energy, first and second storage condensers connected inparallel across said source to be simultaneously charged thereby, acontrol gap having a predetermined breakdown potential, at triggeringgap having a breakdown potential less than that of said control gap, acontrol circuit comprising said condensers and said gaps in series, atriggering breakdown potential of said triggering gap.

12. Apparatus as defined in claim 11 comprising a second source ofelectrical energy for alternatively charging said first condenser to thebreakdown voltage of said control gap, and

means for isolating said second source from said second condenser.

13. Apparatus as defined in claim 12 wherein said isolating means is adiode.

1. Electrical apparatus having a source of electrical energy, amultisection storage condenser connected to said source so as to beincrementally charged thereby with sections of the condenser connectedin parallel, a load circuit including a discharge gap connected to beenergized by the discharge of one section of the storage condenser, afirst control gap interposed between said one section of the storagecondenser and the discharge gap, a second control gap having a breakdownpotential less than that of the first control gap and less than thevoltage of the charge attainable by the parallel connected sections ofthe storage condenser, first circuit means connecting the second gap toanother section of the storage condenser to that the second gap isionized and rendered conductive when the charge on the parallelconnected sections of the storage condenser reaches the breakdownpotential of said second gap, and second circuit means for thereuponconnecting said sections of the storage condenser in series andsubjecting the first gap to the full voltage of the series connectedsections of the storage condenser to as to ionize the first gap andrender the same conductive to discharge said one section of the storagecondenser to the discharge gap independently of the second gap. 2.Electrical apparatus according to claim 1 wherein the storage condenserhas two sections, and the second circuit means includes the second gapinterposed between the junction between the condenser sections and acommon conductor to which the load circuit is connected.
 3. Electricalapparatus according to claim 1 wherein said one section of the storagecondenser has a capacity which is substantially greater than that of theother condenser section.
 4. Electrical apparatus according to claim 1wherein the discharge gap is a shunted surface gap.
 5. Electricalapparatus according to claim 1 comprising a choke coil interposedbetween the first control gap and the discharge gap.
 6. Electricalapparatus according to claim 4 wherein the spark-over voltage of thedischarge gap is less than the breakdown potential of the first gap. 7.Electrical apparatus according to claim 1 wherein the breakdownpotential of the first gap is less than the sum of the voltages of thecharges attained by said sections of the storage condenser when thesecond gap is ionized.
 8. A dual-energy electrical pulse generatingapparatus having two sources of electrical energy, a multisectionstorage condenser, means selectively connecting the condenser to a firstof said sources so as to be incrementally charged thereby with thesections of the condenser connected in parallel, a load circuitconnected to be energized by the discharge of the storage condenser, afirst control gap interposed between at least one section of the storagecondenser and the load circuit, a second control gap having a breakdownpotential substantially less than that oF the first control gap and lessthan the voltage of the parallel connected sections of the storagecondenser as charged by said first source, first circuit meansconnecting the second gap to the storage condenser so that the secondgap is ionized and discharged when the parallel connected sections ofthe storage condenser reach their charged condition, and second circuitmeans for thereupon connecting said sections of the storage condenser inseries and subjecting the first gap to the full voltage of the seriesconnected sections of the storage condenser so as to ionize the firstgap and discharge said one section of the storage condenser to the loadcircuit, and alternatively operated means selectively connecting saidone section only of the storage condenser across the second of saidsources to be charged thereby, whereby the first control gap is thendischarged when the charge on the said one section of the storagecondenser attains the breakdown potential of the first gap.
 9. Adual-energy electrical pulse generating apparatus according to claim 16,wherein said one section of the storage condenser substantially exceedsthe other section thereof in capacity, and the second source ofelectrical energy has a potential greater than that of the first source.10. Electrical pulse generating apparatus comprising a source ofelectrical energy, first and second storage condensers connected inparallel across said source to be simultaneously charged thereby, acontrol gap having a predetermined breakdown potential, a triggering gaphaving a breakdown potential less than that of said control gap, acontrol circuit comprising said condensers and said gaps in series, atriggering circuit comprising said second condenser and said triggeringgap in series, whereby said triggering gap is rendered conductive by thecharge on said second condenser when it attains the breakdown potentialof said triggering gap, thereby connecting said condensers in seriesacross said control gap to render the latter conductive, and a loadcircuit including a load connected in series with said control gapacross said first condenser independently of the triggering gap. 11.Apparatus as defined in claim 10 wherein said load includes a spark gaphaving a spark-over voltage less than the breakdown potential of saidtriggering gap.
 12. Apparatus as defined in claim 11 comprising a secondsource of electrical energy for alternatively charging said firstcondenser to the breakdown voltage of said control gap, and means forisolating said second source from said second condenser.
 13. Apparatusas defined in claim 12 wherein said isolating means is a diode.